In a variable-speed, constant-frequency (VSCF) power generating system, variable-frequency power produced by a brushless, synchronous generator may be converted by a power converter into constant-frequency AC power. The power converter includes a rectifier bridge for converting the variable-frequency power into DC power on DC link conductors, a transient suppressor for dissipating transients on the DC link conductors and an inverter for converting the DC power into the constant-frequency AC power. The inverter may be, for example, of the neutral point clamped type having positive and negative switch assemblies connected in series across the DC link conductors and a neutral switch assembly connected between a neutral voltage and a junction between the positive and negative switch assemblies.
Such VSCF systems are often used in aircraft or aerospace environments where space is at a premium, and hence it is desirable to minimize the size of the system. However, the rectifier bridge, transient suppressor and inverter include high power components which generate substantial amounts of heat that must be removed from the vicinity of the system. The need to remove this heat complicates the physical design of the system and has, in the past, limited the degree to which the size of the system can be reduced.
It is necessary that the connections to the electrodes of the high power devices have as little resistance as possible to minimize power dissipation and heat generation. Typically, this is accomplished by applying compressive force to the devices themselves, in turn insuring intimate physical contact of the electrodes with other components. This further complicates the physical design of the system.
Sutrina, U.S. Pat. No. 4,631,573, assigned to the assignee of the instant application, discloses a cooling system for stacked semiconductors. The cooling system includes a plurality of heat sinks each including planar opposed surfaces and fluid flow ports. The heat sinks are arranged in pairs such that planar faces of the sinks of each pair are adjacent one another with an electrically insulating sheet is disposed therebetween. The pairs are arranged relative to one another to form spaces therebetween and semiconductors are disposed in the spaces. The resulting stack is maintained in assembled relation by a clamp. The heat sinks are interconnected by electrically insulative tubing and the interconnected heat sinks are provided cooling fluid which removes heat from the semiconductors.
Felkel, U.S. Pat. No. 3,913,003 discloses a plurality of stacked building blocks which together make up a power converter.